Grinding cement material, etc.



Nov. 22,- 1927.

E. Z. DALGAARD GRINDING CEMENT MATERIAL, ETC

Filed July 30,. 1926 MJ? C Patented Nov. 22, 1927.

Unirse y Nsra PA rE Nr oFF-Ice. i A

animany znu'rmm DALGAARD; on cernnnnenm nennt-Ann, AssiGN/oit "rei F". L.

siltrntrnj @a oo'.,` on' Naw- Yonx; NL n conrenn'rion or NEW JERSEY.

GRINDING' CEMENT MAH?ERIIHI.,` ETC.

In the grinding of.u cementy material it has been found that for, some purposeshighly` desirable results are secured.` by nvery. fine grinding of. the cement` material.4 lt. has been foundV also, on` the other hand that in: grinding cement. material. to` an extreme degree of fineness in ball" mills" or tube mills which rotate-.on aA substantially horizontal axis and' in which thefcharge of` grinding.v bodies andmateriall is. subjected, by.V reason of the` rotation ofy the.. mill, to a continuous tumbling and` grinding action, therek is an. increasingl tendency of' the. very finely ground material to adhere to. the". grindingk bodies andi toV form upon each. of` them la. pellicle which considerably decreases the grinding efficiency.` of: the grinding bodies,- with a consequent decrease in.. the output. ofl the mill. In accordance with this inver tion, such. coating off theA grinding, bodies witliia filmofthe finelydiVidedmateriaL-at least t0 an injurious degree, is prevented without stopping the. operation: of` the mili by freeing the grinding bodies-asthey apr preach the discharge end off the mill, from the accumulating pellicl-ej` and'` returning them to the mill, preferably at or near the feed end, for further action upon the material. Such lcleansing of the grinding bodies can be accomplished, if the accumulation of material has not been allowed `to proceed too far, by any one of several different methods, as by passing the grinding bodies through a suitable chemical bath or by subjecting them to a blast of air or preferably, as explained hereinafter, by returning them from the discharge end of the mill, Where the material has been reduced to the utmost lineness, to the feed end of the mill where, by the attrition of the coarser particles of material, found at the feed end of the mill, the incipient film of material is removed.

The invention will be explained more fully hereinafter with reference to the accompanying drawing, in which is illustrated one form of apparatus adapted for the practice of the method by the attrition of the relatively coarse particles of material and in which:

Figure 1 is a view in longitudinal central section of so much of a grinding mill as is necessary to enable the invention to be un` derstood.

Y Figure 2 is a view in transverse section 12558723. and` in DenmarkAugust:.14, 1925.

on the plane indicated by the line 2;-2of

Figure l. looking in: the` direction` ofV the` 3PT-OWS. v

The mill. itself,l except ashereinafter indie cated, may becf any usual-.or suitable conw structiombemg shown as-- having. a; metallic.

sliell. l. and.v alining. suitable materi'ah and, i as usual iusuch` mills, rotates onasubstantially horizontal. axis, so that thecharge of. grinding, bodies and.` material issubjected, by reason` of. therotation ofthe mill, toa. continuous tumbling and` `g'rinding action.A The mill'lis shownas having at the feed end a: doubleV wallf 2. with` radially dis-1,

posed lifters Qbywhich the materialisfed into. thegrindingchamben and as havingat the discharge end a double wall 3 equipped with suitably disposedr lifters/ t by which the finely, groundY material. is delivered: intoV the discharg-i.trunmonl 5. Supported. centrally within the shell.' byany convenient 1rieans,stich.l asthestrapsV 1.2. and bolts 13: is-

a tube 7 which rotates withit-he shell@ ofithe mill and. isrequipped. internally withy a.l wormf conveyor- 8 whicnis.- so disposed with reference.A to the directionl ofl rotationA of 'the millthat the bodies delivered into the tube at its forward or right-hand end will be caused to travel through Athe tube and to be delivered therefrom through openings 9, provided near the feed end of the mill, into the grinding chamber at orinear the feed end. At the forward or right-hand end of the tube, `which is close, the tube is equipped with lifters l0 which lift the grinding bodies together with a relatively small proportion of the material, thereby effecting a partial separation of the grinding bodies from the material at or near the right-hand or discharge end of the mill and return the same through openings 1ly into the tube 7 so that they may be transferred to the grinding chamber at the feed end. The grinding bodies which, in their progress through the grinding chamber, become slightly coated with the adhering finely ground material, are thus transported from the discharge end of the grinding chamber through the tube 7 and are returned to the grinding chamber near the feed end of the same, where the material being operated upon has not yet been reduced to a very tine condition but consists of relatively large pieces, by the attrition of which the grinding bodies are freed of the adhering film and are therefore placed again in condltion"fonoperation with maximum eiiiciency. i

It will be understood that so far `as the iIlYeIltOnwindsexpression in a" method, it`

can be ractieed nWays i otherthan that speoica ly described herein and that so far as it nds expression in apparatus, the apparatusmay be varied to suit different conditions of use or the convenience of the manufacturer or the user.

I claim as myinvention l Y `1I The improvement inthe method of fine grinding with grinding bodies in substantially-horizontalrotating mills, which consists infeeding at one end the coarse material which is to be groiuid, progressively and continuouslyv subjecting the' material operated upon to the action of the grinding bodies -through a movement of rotation,

` separatin the grinding bodies from the material Wit iin the mill, freeing the' grinding bodies from the adhering pellicle of iinely ground material within the mill by attrition with the coarse material; and continuing the grinding; ,with the "grinding `bodies thus `treed from the pellicle oflinely` ground mit terial.

2, A grinding mill for grinding with grinding `bodies comprising a substantially horizontal rotating i grinding chamber, means to deliver into the same at the feed end'the material to be ground, ineansto discharge the iinely groiindniaterial at the` other end, and means to separate the grinding `,bodies fromthematerialin the grinding chamber near the discharge end and return them Within the grinding chamber to `a point in the chamber near the feed end to bejmingled there with the relatively coarser material.

3. A grinding mill for grinding with grinding bodies comprising substantially grinding chamber near the discharge end, al

conveyor' Within the chamba-,means to de-f liver to theconveyor such grinding bodies, and means to deliver such grinding bodies` from theV conveyor Within the grinding chamber. at a point `near `the feedend there l. A grinding mill" for V,grinding with" grinding bodiescomprising a cylindrical` shell forming agrinding@chamber, means to deliver feed end the material tobe ground, means to discharge from the grinding chamber at to thefgrnding chamber at its the other end the finely ground material, a

conveyor tube supported centrally ivithinthe cylindrical shell and rotating tberewitli,Y` means to deliver grinding bodies i'roiii" tha grinding chamber near its discharge endto" and means to discharge the conveyor tube,

such grinding bodies from the conveyor tube intoi end.

muy, in D; i926.

the grinding chamber Anear its feed"V This speciiicationsigned tliisfi'th day ot nnviinn ZEUTHEN DALoAAnn, 

